CHAP. III.] iiKHLETON OF THE HEAD AND TRUNK. 



53 



thus tends, by filling up depressions, to render tlic surface of tlio 

 vertebral column more even. 



Another band of fibres, called the dorsal common ligament, passes 

 backwards within the neural canal along its ventral surface from the 

 skull backwards. 



Eacli pair of articulating z3^gapopbyses is surrounded and enclosed 

 by a fibrous bag, the fibres passing from one zygapopbysis to tlie 

 other. Such a surrounding and enclosing membrane is termed a 

 capsular Urjament. Enclosed within the capsular ligament is a 



Fi£'. 20. — Intervertebral Disc;. 



A. Surface view enlarged. 



B. Section tlirougli two di.ses. 

 /. IjauMjlUt. 



g. Scift pentral portion. 

 ■(. lutersxiinous ligaments. 



membrane which secretes an albuminous fluid termed synovia. 

 Membranes of the kind are therefore termed synovial, and are 

 placed between hard parts which are destined to move one on the 

 other. Synovial membranes will be more fidly noticed in the descrip- 

 tion of the different kinds of joints at the end of the next chapter. 



Certain Hgaments with much yellow elastic tissue, called the liga- 

 menta suhjiava, pass between the neural lamina, being attached to the 

 umer or ventral surface on one neural lamina and thence passing 

 backwards to the anterior margin of the neural lamina next behind. 

 They are thus best seen when the neural arches are removed and 

 viewed on their ventral aspect. 



